Bun's Lab – Telegram
Bun's Lab
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Electronics projects, vintæg computing, programming and repairs. A minimalist blog of sorts.
@BunsGarden @BunsNook
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The CRT board is a third party daughter board. Computron 115DMX. Those bastards filed off the label of the controller IC
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Black screen. The flyback is running however
The heater is glowing. So I got heater voltage, put the cable in the correct way and didn't neck the tube.

God, how I love CRTs. Little electron particle accelerators <3
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Got a video signal. So what gives?
There we go. Brightness pot slipped a bit during handling of the board lol
1
Measuring the voltage at the capacitor: it's just 50V DC. So, using 2.2u is fine
Trying to charge the NiCd battery with my lab supply: nothing. Dead. And I don't have replacements here. So that's gotta wait.
There's a floppy drive hidden beneath a flap on the top. I have a policy of checking, cleaning and servicing any and all floppy drives in my machines.
With all the sud that came off the CRT screen, I was expecting a lot more dirt. Basically clean.

It's a Panasonic JU-455-5 double sided double density drive, so 360kB formatted.
The controller board lives directly underneath the drive. It's got a uPD765 floppy drive controller, a
uPD8257 DMA Controller, and a uPB9201 floppy disk interface controller, flanked by 8x8K of static RAM.
Interesting design to have extra RAM on here.
The controller board lives directly underneath the drive. It's got a uPD765 floppy drive controller, a
uPD8257 DMA Controller, and a uPB9201 floppy disk interface controller, flanked by 8x8K of static RAM.
Interesting design to have extra RAM on here.